Pore fluids from the upper 60 meters of sediment 3000 meters below the surface of the tropical Atlantic indicate that the oxygen isotopic composition (delta18O) of seawater at this site during the last glacial maximum was 0.8 ± 0.1 per mil higher than it is today. Combined with the delta18O change in benthic foraminifera from this region, the elevated ratio indicates that the temperature of deep water in the tropical Atlantic Ocean was 4°C colder during the last glacial maximum. Extrapolation from this site to a global average suggests that the ice volume contribution to the change in delta18O of foraminifera is 1.0 per mil, which partially reconciles the foraminiferal oxygen isotope record of tropical sea surface temperatures with estimates from Barbados corals and terrestrial climate proxies.

Strontium/calcium ratios in deep-sea carbonate sediments have been used as recorders of paleoceanographic Sr/Ca and as indicators of diagenetic alteration of calcite sediments. We evaluate the relative impacts of ocean history and calcite recrystallization on bulk calcite Sr/Ca records from sediments from the Ceara Rise (CR) and the equatorial PaciÞc. We present Sr/Ca and Mg/Ca data from bulk calcite analyses of samples from the range of depths drilled at the Þve sites in the Ocean Drilling Program (ODP) Leg 154 Ceara Rise depth transect. The Sr/Ca and Mg/Ca records appear to vary more consistently with age than with sediment depth, indicating that they more strongly represent records of oceanic Sr/Ca and Mg/Ca ratios, rather than depthcontrolled diagenetic alteration. We compare Sr/Ca records from the CR with bulk calcite records from the Ontong Java Plateau (OJP) in the western equatorial PaciÞc (Leg 130, Sites 803-807) and the eastern equatorial PaciÞc (EEqP; ODP Leg 138, Sites 844-846, 851, and 853), and with a planktonic foraminifer record. All Sr/Ca records show similar trends, with Sr/Ca values increasing to the present and large ßuctuations superimposed on this trend in the Neogene. We use quantitative estimates of celestite (SrSO 4) saturation in pore waters and a Sr-exchange model of calcite diagenesis to evaluate the potential inßuence of authigenic SrSO 4 precipitation on the bulk calcite Sr/Ca from the CR, OJP, and EEqP. We conclude that celestite does not precipitate in the EEqP sites and probably does precipitate at most or all CR and OJP sites. We further conclude that the precipitation of SrSO 4 at some sites and not others accounts for only a small fraction of the differences in contemporaneous Sr/Ca values in calcite.

Oxygen isotope measurements of interstitial waters from Ocean Drilling Program Leg 154, sampled at high resolution from Sites 925 and 929, are used to reconstruct the oxygen isotopic composition of deep water during the last glacial maximum (LGM). The data from both sites show an increase with depth, predicted by modeling the diffusion of water through the sediment, although only data from Hole 925E are appropriate for calculating the composition of seawater during the LGM. Using a numerical model to simulate diffusion of water in the sediments, we obtained a glacial-interglacial change in the d 18 O of seawater at Site 925 of 0.8 ± 0.1ä. This implies that the bottom water at Site 925 cooled by approximately 4ûC during the LGM. Although these data from a single site do not represent a global average, we suggest that the substantial cooling of deep water at Site 925 is consistent with a global average change in the d 18 O of seawater of 1.0ä. This value is within the limits imposed by the freezing point of seawater and is more consistent with estimates of the d 18 O of continental ice during the glacial maximum. In addition, a lower contribution from ice volume to the change in d 18 O of planktonic foraminifers allows for 1û-2û additional cooling in the tropics during the LGM, partially reconciling the foraminiferal oxygen isotope record of tropical sea surface temperatures with estimates from Barbados corals and terrestrial climate proxies.

Scleractinian and rugose corals demonstrate a broad environmental distribution and have been documented in strata reflecting deposition from high-energy, nearshore reefal to low-energy basinal settings. Both clades have a relatively high diversity of representatives which live(d) at great depths. While deep-water scleractinian coral banks are" well-documented, commonly the deep-water representatives of both clades are the small, solitary, and often delicate forms. In order to determine the nature of diversification of these deep-water forms the paleoenvironments of the earliest Rugosa and representatives of extant deep-water scleractinian families were determined. Environmental patterns of the subsequentdiversification of the Rugosa and scleractinian sub-order Caryophylliina were also documented. Environmental information was determined from independent sedimentological data.